The invention relates to incandescent lamp and glass reflector combinations for use in projection systems such as 16 mm. movie projectors.
In many projection units which include a preformed glass reflector and projection lamp, e.g. tungsten halogen, therein, the lamp is retained in alignment with the reflector by employing a suitable cement, e.g. sauereisen, within the reflector and about the lamp's sealed end. Examples of such arrangements are shown in U.S. Pat. Nos. 3,314,331 (Wiley) and 3,639,750 (Anthonijsz). Use of cement of a similar permanent-type bonding agent prohibits separation of the lamp and reflector in the event that replacement of either of these components is necessary. In almost all cases, it is only the incandescent lamp which fails and needs replacement. The aforementioned permanent bond between lamp and glass reflector was believed essential to assure precise alignment between said components and between these members and other elements (e.g. film gate, projection lens) within the overall system. Alignment between reflector and lamp was usually achieved using a precisioned instrument whereupon the assembled unit was ready for insertion within a respective socket-holder arrangement, such as shown in U.S. Pat. No. 3,789,212 (Wagner). This latter positioning is usually accomplished by the projector's operator.
Mandatory replacement of both lamp and glass reflector has therefore resulted in unnecessary waste of material which in turn has added appreciably to the overall cost of operating such systems.
The projection unit of Ser. No. 829,793 was designed to eliminate the above undesired requirement by providing a retention member which is removable from within the reflector yet also assures positive alignment of the unit's incandescent lamp with the reflector when said lamp is positioned therein. The retention member is secured to the lamp's sealed end and may comprise a metallic "can", a preformed component of insulative material such as ceramic, or a combination of both.
The present invention represents an improvement to the unit of Ser. No. 829,793 by providing means whereby the retention member having the sealed end of the lamp therein may be removed from the front, concave reflecting portion of the glass reflector. The method of removal for these components in Ser. No. 829,793 is through the rear, neck portion of the reflector. This requirement necessitates provision of a relatively large opening within the neck portion and, as a result, the lamp's total forward output is reduced. Rearward removal of the lamp is also somewhat difficult due to the limited accessibility of this portion of the unit within the overall system.
It can therefore be seen that a projection unit which permits forward removal of the unit's incandescent lamp from the glass reflector would constitute an advancement in the art.